Primary in vitro generation of cytotoxic cells specific for human minor histocompatibility antigens between HLA-identical siblings.

A limiting dilution culture system was developed for the primary in vitro detection of human minor histocompatibility antigens by cytotoxic T lymphocytes (CTL). CTL were generated in primary in vitro culture between two HLA-identical sibling pairs and propagated as stable CTL lines. Population and family studies indicate that these CTL lines recognize minor histocompatibility antigens in an HLA-restricted manner. The antigen recognized by one CTL line is detected on six (out of 37) HLA-B7-positive donors but not on 32 HLA-B7-negative donors. The cytotoxicity of this CTL line is mediated by T3+, T8+ effector cells. The antigen detected by this CTL population is different from all known human minor histocompatibility antigens. The data of this study, like those in the mouse system, suggest that a suppressor cell is diluted out in a limiting dilution culture, which allows the activation of the CTL precursors.